Atmospheric Environment (v.97, #C)
Encounters with Atmospheric Environment by Peter Brimblecombe (A1-A3).
Editorial board (i).
Editorial for Peter Brimblecombe Virtual Special Issue (VSI) by Hanwant B. Singh (A4-A5).
Micro-scale (μg) radiocarbon analysis of water-soluble organic carbon in aerosol samples by Yan-lin Zhang; Jun-wen Liu; Gary A. Salazar; Jun Li; Peter Zotter; Gan Zhang; Rong-rong Shen; Klaus Schäfer; Jürgen Schnelle-Kreis; André S.H. Prévôt; Sönke Szidat (1-5).
Radiocarbon (14C) measurement of water-soluble organic carbon (WSOC) in ambient aerosols is a quantitative tool for unambiguously distinguishing fossil and non-fossil sources. In this study, a fast and reliable method for measuring 14C in micro-scale (μg) WSOC aerosol samples is successfully developed, which includes three steps: (1) extraction (2) freeze drying, and (3) online 14C analysis of CO2 from WSOC combustion. Procedure blanks are carefully assessed by measuring high-purity water and reference materials. Accurate 14C results could be obtained for WSOC with only 10 μg C, and thus the potential applications are substantially broadened because much less filter material is needed compared to previous reported methods. This method is applied to aerosols samples collected during winter from Switzerland and China. The results demonstrate that non-fossil sources are important if not dominant contributors of WSOC. These non-fossil components are consistently enriched in WSOC compared to bulk OC and water-insoluble OC for all samples, due to high water solubility of primary and secondary biomass burning aerosols. However, the presence of fossil WSOC is still considerable indicating a substantial contribution of secondary OC (SOC) formed from precursors emitted by fossil emissions. Larger fossil contributions to WSOC is found in China than in Switzerland and previously reported values in Europe, USA and South Asia, which may be attributed to higher fossil-derived SOC formation in China.
Keywords: Aerosols; Radiocarbon 14C; Water-soluble organic carbon; Source;
Near-surface ozone trends over Europe in RegCM3/CAMx simulations for the time period 1996–2006 by D. Akritidis; P. Zanis; I. Pytharoulis; Th. Karacostas (6-18).
The RegCM3/CAMx modeling system is applied to estimate near surface ozone trends over Europe for the time period 1996–2006. In order to assess the impact of changing anthropogenic emissions and meteorology on modeled ozone trends two simulations were performed: The first simulation (CONEM) was forced from constant anthropogenic emissions based on the EMEP emissions of the year 1996, while the second simulation (VAREM) was forced from year to year varying anthropogenic emissions based on the EMEP emissions of the years 1996–2006.Near surface ozone measurements from the EMEP database are used for assessing the skill of the modeling system to reproduce the observed ozone trends. Concerning VAREM simulation the main pattern is a significant positive annual trend over southern UK and Benelux which is also detected in the observations, attributed to the reduction of ozone titration by NO as a result of NO x emissions control policies. Significant negative ozone trends are found over the Mediterranean due to reduction of ozone precursors emissions over continental Europe. As far as it concerns CONEM simulation a significant increase of ozone is found during summer associated with the heatwave event of 2003. Overall, the observed ozone trends are captured fairly well by the RegCM3/CAMx modeling system over the highly polluted areas of central and western Europe but only partially reproduced or not captured at all at the rest of Europe, probably due to limitations of the model setup to capture background ozone variability related to processes such as intercontinental transport and stratosphere–troposphere exchange.
Keywords: Near surface ozone; Trend; Air quality modeling; Anthropogenic emissions; Europe;
Magnetic biomonitoring by moss bags for industry-derived air pollution in SW Finland by Hanna Salo; Joni Mäkinen (19-27).
We provide the first detailed case study using Sphagnum papillosum moss bags for active magnetic monitoring of airborne industrial pollution in order to evaluate the actual role of various emission sources and the competence of current environmental protection actions relative to the air quality. The origin and spatial spreading of particulate matter (PM) based on magnetic, chemical, and SEM-EDX analyses was studied around the Industrial Park in Harjavalta, SW Finland. The data was collected during two 6-month sampling periods along 8 km transects in 2010–2011. The results support our hypothesis that the main emission source of PM is not the Cu–Ni smelter's pipe as presumed in previous chemical monitorings. We argue that the hot spot area within the severe impact pollution zone is related to slag processing and/or other unidentified industrial activity. At short distances various dust-providing sources outweigh the fly-ash load from the Cu–Ni smelter's pipe. Active magnetic monitoring by moss bags will help in planning environmental actions as well as in improvement of health conditions for industrial staff and town residents living next to the Industrial Park.
Keywords: Air pollution; Moss bag; Environmental magnetism; Heavy metals;
Compound-specific hydrogen isotope composition of n-alkanes in combustion residuals of fossil fuels by Huiling Bai; Lin Peng; Zhongping Li; Xiaofeng Liu; Chongfang Song; Ling Mu (28-34).
The hydrogen isotope compositions (δD) of n-alkanes present in the combustion residuals of fossil fuels (coal, gasoline, and diesel) were measured using GC-IRMS to distinguish between coal soot and vehicle exhaust. The n-alkane δD values of industrial and domestic coal soot ranged from −95.3‰ to −219.6‰ and −128.1‰ to −188.6‰, respectively, exhibiting similar tendencies. The δD values of the C15–C18 n-alkanes in both types of coal soot were nearly consistent, and the δD values of the C19–C24 n-alkanes exhibited a zigzag profile. The δD values of C16–C22 n-alkanes in gasoline exhaust exhibited a saw-tooth distribution, decreased with the carbon number, and were more positive than the δD values of C16–C22 n-alkanes in diesel exhaust, which increased with the carbon number. However, the δD values of the C23–C29 n-alkanes in gasoline and diesel vehicle exhaust were mostly consistent. The weighted average δD values of the C16–C19 n-alkanes in industrial and domestic coal soot were similar to the average δD values in gasoline and diesel vehicle exhausts; however, the average δD values of the C21–C29 n-alkanes in vehicle exhausts were richer in D than those in coal soot.
Keywords: Hydrogen isotope composition (δD); n-Alkanes; Vehicle exhaust; Coal soot;
Airborne endotoxin in fine particulate matter in Beijing by Tianjia Guan; Maosheng Yao; Junxia Wang; Yanhua Fang; Songhe Hu; Yan Wang; Anindita Dutta; Junnan Yang; Yusheng Wu; Min Hu; Tong Zhu (35-42).
Endotoxin is an important biological component of particulate matter (PM) which, upon inhalation, can induce adverse health effects, and also possibly complicate the diseases in combination with other pollutants. From 1 March 2012 to 27 February 2013 we collected air samples using quartz filters daily for the quantification of airborne endotoxin and also fine PM (PM2.5) in Beijing, China. The geometric means for endotoxin concentration and the fraction of endotoxin in PM were 0.65 EU/m3 (range: 0.10–75.02) and 10.25 EU/mg PM2.5 (range: 0.38–1627.29), respectively. The endotoxin concentrations were shown to vary greatly with seasons, typically with high values in the spring and winter seasons. Temperature and relative humidity, as well as concentrations of sulfur dioxide and nitrogen oxides were found to be significantly correlated with airborne endotoxin concentrations (p < 0.05). Additionally, positive correlations were also detected between endotoxin concentrations and natural sources of Na+, K+, Mg2+, and F−, while negative correlations were observed between endotoxin concentrations and anthropogenic sources of P, Co, Zn, As, and Tl. Oxidative potential analysis revealed that endotoxin concentrations were positively correlated with reactive oxygen species (ROS), but not dithiothreitol (DTT) of PM. This study provided the first continuous time series of airborne endotoxin concentrations in Beijing, and identifies its potential associations with atmospheric factors. The information developed here can assist in the assessment of health effects of air pollution in Beijing.
Keywords: Endotoxin; Fine particulate matter; Meteorological factors; Gaseous pollutants; Chemical components; Oxidative potential;
Ammonia exhaust emissions from spark ignition vehicles over the New European Driving Cycle by R. Suarez-Bertoa; A.A. Zardini; C. Astorga (43-53).
A study aiming to measure ammonia emissions from light duty vehicles has been performed in the Vehicle Emission Laboratory at the European Commission Joint Research Centre, Ispra, Italy. Ammonia, known for being toxic and dangerous for the environment, also contributes to the formation of particulate matter that has been related with adverse health and environmental effects.Nine modern light duty vehicles tested over the New European Driving Cycle showed that ammonia emissions are considerable for gasoline and ethanol flexi-fuel vehicles and also for one diesel vehicle equipped with a selective catalytic reduction system, ranging from 4 mg/km to 70 mg/km. Real-time ammonia emission profiles were monitored at the tailpipe by a High Resolution Fourier Transform Infrared spectrometer during tests at 22 and/or −7 °C. Ammonia emissions are thoroughly discussed and compared to those of its precursors, CO and NO, and other regulated compounds.
Keywords: Vehicle emissions; Ammonia; Three-Way Catalyst; Raw exhaust measurement;
Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-TOF-MS) determination of volatile organic compounds (VOCs) emitted from a biomass fire developed under stable nocturnal conditions by Federico Brilli; Beniamino Gioli; Paolo Ciccioli; Donatella Zona; Francesco Loreto; Ivan A. Janssens; Reinhart Ceulemans (54-67).
Combustion of solid and liquid fuels is the largest source of potentially toxic volatile organic compounds (VOCs), which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction “Time-of-Flight” Mass Spectrometer (PTR-TOF-MS), which couples high sensitivity with high mass resolution, for real-time detection of multiple VOCs emitted by burned hay and straw in a barn located near our measuring station. We detected 132 different organic ions directly attributable to VOCs emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the VOC mixture composition. The time-course of the 25 most abundant VOCs, representing ∼85% of the whole mixture of VOCs, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic VOC and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of ER (and EF) were overestimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant VOCs in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, the evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic gases recorded.
Keywords: Fire; PTR-TOF-MS; Pyrogenic VOC; Turbulence; Biomass combustion; Excess mixing ratio; Emission ratio; Emission factor;
Half-century nitrogen deposition increase across China: A gridded time-series data set for regional environmental assessments by Chaoqun Lu; Hanqin Tian (68-74).
A wide variety of studies have revealed a substantial increase in nitrogen (N) deposition in China, but the lack of spatially-explicit time-series N deposition data set has long hindered us from assessing the impacts of atmospheric N input on ecosystem services. In this study, we combined site-level monitoring, gridded precipitation data and atmospheric transport modeling results to generate annual N bulk deposition data in China with a spatial resolution of 10 km × 10 km and a time span from 1961 to 2008. It shows that national average N deposition rate had large interannual variation, and it increased by 59%, from 12.64 kg N ha−1 yr−1 in the 1960s to 20.07 kg N ha−1 yr−1 in the recent decade, with the most rapid increase centered in the southeastern China that is already N-enriched. Large spatial variation as well as dry deposition input has to be taken into account when estimating the amount of N deposited onto land surface of China. The spatial and temporal information on N deposition derived from this study could be used by ecosystem, hydrological, and climate modeling as well as by policy makers for assessing the impacts of nitrogen enrichment on regional climate, water resources, and biogeochemical cycles.
Keywords: Nitrogen deposition; China; Increase trend; Spatial distribution;
New atmospheric composition observations in the Karakorum region: Influence of local emissions and large-scale circulation during a summer field campaign by D. Putero; P. Cristofanelli; P. Laj; A. Marinoni; P. Villani; A. Broquet; M. Alborghetti; U. Bonafè; F. Calzolari; R. Duchi; T.C. Landi; G.P. Verza; E. Vuillermoz; P. Bonasoni (75-82).
In this work we provide an overview of short lived climate forcers (SLCFs) and carbon dioxide variability in the Karakorum, by presenting results deriving from a field campaign carried out at Askole (3015 m a.s.l., Pakistan Northern Areas), by Baltoro glacier. By using an innovative embedded and transportable system, continuous measurements of aerosol particle number concentration (Np, 1571 ± 2670 cm−3), surface ozone (O3, 31.7 ± 10.4 nmol/mol), carbon dioxide (CO2, 394.3 ± 6.9 μmol/mol) and meteorological parameters have been performed from August 20th to November 10th 2012. The domestic combustion from the Askole village emerged as a possible systematic source of contamination in the valley, with short-lasting pollution events probably related to domestic cooking activities characterized by high values of Np (6066 ± 5903 cm−3). By excluding these local contamination events, mountain thermal wind regime dominated the diurnal variability of Np, O3 and CO2. In comparison to night-time, we observed higher Np (+354 cm−3) and O3 (+7 nmol/mol) but lower CO2 (−8 μmol/mol) in air-masses coming from the lower valley during the central part of the day. Part of the day-to-day atmospheric composition variability can be also ascribed to synoptic circulation variability, as observed by using HYSPLIT 5-day back-trajectories.
Keywords: Surface ozone; Aerosol particles; Carbon dioxide; Karakorum; Anthropogenic pollution;
Indoor–outdoor levels of size segregated particulate matter and mono/polycyclic aromatic hydrocarbons among urban areas using solid fuels for heating by Linas Kliucininkas; Edvinas Krugly; Inga Stasiulaitiene; Inga Radziuniene; Tadas Prasauskas; Arunas Jonusas; Violeta Kauneliene; Dainius Martuzevicius (83-93).
Emissions from the fuel combustion in the energy production are causes of concern due to associated health risks, but little information is available on the impact of residential fuel burning on indoor air quality, where most of the human exposure occurs. In this complex study, concentrations of size-segregated particulate matter (PM), monocyclic and polycyclic aromatic compounds (MAHs and PAHs) at indoor and outdoor sites in six urban homes in the city of Kaunas, Lithuania, were determined over winter and summer sampling campaigns, specifically targeting the impact of the local fuel burning to the indoor air quality. PM levels observed in Kaunas during winter measurement campaign were higher compared to those in many other European settlements utilizing biomass for energy production. The particle size distribution analysis revealed that the major part of the PM mass in winter period consisted of fine particles (PM2.5). Both MAH and PAH levels were higher in winter. The indoor to outdoor ratios (I/O) of MAHs and PAHs revealed specific patterns depending on the presence of emissions sources indoors. Irrespectively of the season, I/O values were <1, suggesting that in case of the absence of an indoor pollution, the dominant source of organic compounds was from the outdoor environment. In homes with no PAH source inside, the I/O ratio equalled ranged from 0.05 to 0.36, suggesting the penetrated portion of outdoor combustion particles to the indoor air.
Keywords: Fuel burning pollution; Solid fuel; Biomass; Indoor air quality; Particulate matter; MAHs; PAHs; Indoor/outdoor;
Removing traffic emissions from CO2 time series measured at a tall tower using mobile measurements and transport modeling by Andres Schmidt; Chris W. Rella; Mathias Göckede; Chad Hanson; Zhenlin Yang; Beverly E. Law (94-108).
In recent years, measurements of atmospheric carbon dioxide with high precision and accuracy have become increasingly important for climate change research, in particular to inform terrestrial biosphere models. Anthropogenic carbon dioxide emissions from fossil fuel burning have long been recognized to contribute a significant portion of the carbon dioxide in the atmosphere. Here, we present an approach to remove the traffic related carbon dioxide emissions from mole fractions measured at a tall tower by using the corresponding carbon monoxide measurements in combination with footprint analyses and transport modeling. This technique improves the suitability of the CO2 data to be used in inverse modeling approaches of atmosphere–biosphere exchange that do not account for non-biotic portions of CO2. In our study region in Oregon, road traffic emissions are the biggest source of anthropogenic carbon dioxide and carbon monoxide. A three-day mobile campaign covering 1700 km of roads in northwestern Oregon was performed during summer of 2012 using a laser-based Cavity Ring-Down Spectrometer. The mobile measurements incorporated different roads including main highways, urban streets, and back-roads, largely within the typical footprint of a tall CO/CO2 observation tower in Oregon's Willamette Valley. For the first time, traffic related CO:CO2 emission ratios were measured directly at the sources during an on-road campaign under a variety of different driving conditions. An average emission ratio of 7.43 (±1.80) ppb CO per ppm CO2 was obtained for the study region and applied to separate the traffic related portion of CO2 from the mole fraction time series. The road traffic related portion of the CO2 mole fractions measured at the tower site reached maximum values ranging from 9.8 to 12 ppm, depending on the height above the surface, during summer 2012.
Keywords: High precision carbon dioxide observations; Traffic emissions; Transport modeling;
A review of receptor modelling of industrially emitted particulate matter by Adewale M. Taiwo; Roy M. Harrison; Zongbo Shi (109-120).
This review summarizes the different receptor models that have been adopted at industrial and urban sites to apportion the sources of particulate matter (PM) from industries. Industrial processes and those associated with industry (such as transportation) are an important source of airborne PM which includes trace elements, organic and elemental carbon, and PAHs. Industry also emits gaseous pollutants which form secondary aerosol in the atmosphere. Most published studies have employed chemical mass balance (CMB), positive matrix factorization (PMF) and/or principal component analysis (PCA) models as source apportionment tools. These receptor models were mostly applied to fine particulate matter (PM2.5) and PM10 compositional data, particularly the inorganic constituents. Some studies have combined two or more of these receptor models, which provides useful information on the uncertainties associated with different models. Industry has been reported to contribute from 0 to 70% of PM mass at industrial sites. It appears that some studies are unsuccessful in apportioning PM from industry, e.g., unable to distinguish industrial emissions from other sources. A critical evaluation of the literature data also showed that the choice of appropriate tracers for industry, both generically and for specific industries, varies between different PM source apportionment studies. This is not surprising considering the significant difference in source profiles of PM from different types of industry, which may compromise source apportionment of industrial emissions using CMB with non-local source profiles. It may also affect the attribution of industrial emissions in multivariate statistical models (e.g. PMF and PCA). It is concluded that a general classification of the source “industry” is rarely appropriate for PM source apportionment. Indeed, such studies may even need to consider the different processes within a particular industry, such as a steelworks, which emit PM with significantly different chemical signatures. It is suggested that future source apportionment studies should make every effort to measure source profiles of PM from different industrial processes, and where possible, use multiple models in order to more accurately apportion the source emissions from industry.
Keywords: Source apportionment; Industrial emissions; Receptor modelling; Metals; Particulate matter; Steel industry;
GIS based assessment of the spatial representativeness of air quality monitoring stations using pollutant emissions data by G. Righini; A. Cappelletti; A. Ciucci; G. Cremona; A. Piersanti; L. Vitali; L. Ciancarella (121-129).
Spatial representativeness of air quality monitoring stations is a critical parameter when choosing location of sites and assessing effects on population to long term exposure to air pollution. According to literature, the spatial representativeness of a monitoring site is related to the variability of pollutants concentrations around the site.As the spatial distribution of primary pollutants concentration is strongly correlated to the allocation of corresponding emissions, in this work a methodology is presented to preliminarily assess spatial representativeness of a monitoring site by analysing the spatial variation of emissions around it. An analysis of horizontal variability of several pollutants emissions was carried out by means of Geographic Information System using a neighbourhood statistic function; the rationale is that if the variability of emissions around a site is low, the spatial representativeness of this site is high consequently.The methodology was applied to detect spatial representativeness of selected Italian monitoring stations, located in Northern and Central Italy and classified as urban background or rural background. Spatialized emission data produced by the national air quality model MINNI, covering entire Italian territory at spatial resolution of 4 × 4 km2, were processed and analysed.The methodology has shown significant capability for quick detection of areas with highest emission variability. This approach could be useful to plan new monitoring networks and to approximately estimate horizontal spatial representativeness of existing monitoring sites. Major constraints arise from the limited spatial resolution of the analysis, controlled by the resolution of the emission input data, cell size of 4 × 4 km2, and from the applicability to primary pollutants only.
Keywords: Air pollution; Emissions; Monitoring networks; Spatial representativeness; GIS;
Detrended cross-correlation analysis of temperature, rainfall, PM10 and ambient dioxins in Hong Kong by Kai Shi (130-135).
Using detrended cross-correlation analysis (DCCA), we investigate the long-term influence of some factors, specifically precipitation, average temperature and PM10 concentrations on the evolution of Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) concentrations in Hong Kong. The 15 years regular monitoring data from two general urban sites, Central/Western District and Tsuen Wan, are analyzed. The results show that the relationships between ambient dioxins and precipitation (or PM10) display long-term cross-correlation at the time scale ranging from one month to one year; while, no cross-correlation with each other have observed in longer temporal scaling regimes (greater than one year). Meantime, differentiated from the previous study, we found that precipitation has the greatest influence on ambient PCDD/PCDFs at the long-term time scaling (about one year) in Hong Kong. And no significant relationships are found between ambient dioxins and average temperature at long-term time scale. These results correspond to atmospheric circulation and regional transport hypothesis and are explained in detail. The long-term cross-correlation property is discussed further, considering the strong influence of the Asian monsoon system.
Keywords: Detrended cross-correlation analysis; Polychlorinated dibenzo-p-dioxins; Polychlorinated dibenzofurans; Long-term cross-correlation; Meteorological parameter; PM10;
The application of a multi-wavelength Aethalometer to estimate iron dust and black carbon concentrations in the marine boundary layer of Cape Verde by P. Fialho; M. Cerqueira; C. Pio; J. Cardoso; T. Nunes; D. Custódio; C. Alves; S.M. Almeida; M. Almeida-Silva; M. Reis; F. Rocha (136-143).
The two-component model (Fialho et al., 2006) was used to decouple the contributions of black carbon (BC) and iron oxides, present in dust, to the aerosol attenuation coefficient, measured with a multi-wavelength Aethalometer. The model results were compared with the elemental carbon (EC) and iron concentrations determined in the laboratory from the analysis of aerosol particles collected with conventional samplers. The comparison was based on one year of data obtained at Praia, Santiago Island, Cape Verde, after side by side operation of the aerosol monitoring instruments. The linear regression equation that best describes the relationship between BC concentrations, derived from the Aethalometer, and EC concentrations, derived from a PM10 high-volume sampler after filter analysis with a thermal optical method, presents a slope of 1.01 ± 0.05 and a correlation coefficient (r) of 0.90, showing that the model worked as intended to describe BC concentrations without interferences from iron dust. On the other hand, the linear regression equation that best describes the relationship between the iron concentrations derived from the Aethalometer and elemental iron concentrations, derived from a PM10 low-volume sampler after filter analysis by k0 – Instrumental Neutron Activation Analysis, presents a slope of 0.495 ± 0.014 and a correlation coefficient (r) of 0.96. These results show that the two-component model underestimated the iron concentrations in dust aerosol, which was explained by differences in the size range of particles sampled with the Aethalometer and the PM10 low-volume sampler together with differences in the size distribution of iron oxides.
Keywords: Iron dust; Black carbon; Aethalometer; Two-component model; Cape Verde;
NO x profile around a signalized intersection of busy roadway by Kyung Hwan Kim; Seung-Bok Lee; Sung Ho Woo; Gwi-Nam Bae (144-154).
The NO x pollution profile around a signalized intersection of a busy roadway was investigated to understand the effect of traffic control on urban air pollution. Traffic flow patterns were classified into three categories of quasi-cruising, a combination of deceleration and acceleration, and a combination of deceleration, idling, and acceleration. The spatial distribution of air pollution levels around an intersection could be represented as a quasi-normal distribution, whose peak height was aggravated by increased emissions due to transient driving patterns. The peak concentration of NO x around the signalized intersection for the deceleration, idling, and acceleration category was five times higher than that for the quasi-cruising category. Severe levels of NO x pollution tailed off approximately 400 m from the center of the intersection. Approximately 200–1000 ppb of additional NO x was observed when traffic was decelerating, idling, and accelerating within the intersection zone, resulting in high exposure levels for pedestrians around the intersection. We propose a fluctuating horizontal distribution of motor vehicle-induced air pollutants as a function of time.
Keywords: Traffic control; NO x profile; Urban air pollution; On-road measurement; Intersection;
Source apportionment of single particles sampled at the industrially polluted town of Port Talbot, United Kingdom by ATOFMS by Adewale M. Taiwo; Roy M. Harrison; David C.S. Beddows; Zongbo Shi (155-165).
Single particle analysis of an industrially polluted atmosphere in Port Talbot, South Wales, United Kingdom was conducted using Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS). During the four week sampling campaign, a total of 5,162,018 particles were sized in the size range 0.2–1.9 μm aerodynamic diameter. Of these, 580,798 were successfully ionized generating mass spectra. K-means clustering employed for analysing ATOFMS data utilized 96% of the hit particles to generate 20 clusters. Similar clusters were merged together and 17 clusters were generated from which 7 main particle groups were identified. The particle classes include: K-rich particles (K–CN, K–NO3, K–EC, K–Cl–PO3 and K–HSO4), aged sea salt (Na–NO3), silicate dust (Na–HSiO2), sulphate rich particles (K–HSO4), nitrate rich particles (AlO–NO3), Ca particles (Ca–NO3), carbon-rich particles (Mn–OC, Metallic–EC, EC, EC–NO3 and OC–EC), and aromatic hydrocarbon particles (Arom–CN, Fe–PAH–NO3 and PAH–CN). With the aid of wind sector plots, the K–Cl–PO3 and Na–HSiO2 particle clusters were related to the steelworks blast furnace/sinter plant while Ca-rich particles arose from blast furnace emissions. K–CN, K–EC, Na–HSiO2, K–HSO4, Mn–OC, Arom–CN, Fe–PAH–NO3, and PAH–CN particles were closely linked with emissions from the cokemaking and mills (hot and cold) steelworks sections. The source factors identified by the ATOFMS were compared with those derived from multivariate analysis using Multilinear Engine (ME-2) applied to filter samples analysed off-line. Both methods of source apportionment identified common source factors including those within the steelworks (blast furnace, sinter, cokemaking), as well as marine, traffic and secondary particles, but quantitative attribution of mass is very different.
Keywords: Single particle; Steelworks; Wind sector; Source contribution; ME-2; ATOFMS;
Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies by Gouri Prabhakar; B. Ervens; Z. Wang; L.C. Maudlin; M.M. Coggon; H.H. Jonsson; J.H. Seinfeld; A. Sorooshian (166-173).
This study examines the sources of NO3 − in stratocumulus clouds over the eastern Pacific Ocean off the California coast using airborne and surface measurement data from the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE; 2011) and Nucleation in California Experiment (NiCE; 2013). Average NO3 − air-equivalent concentrations in cloud water samples categorized as having been influenced by ship exhaust (2.5 μg m−3), strong marine emissions (2.5 μg m−3) and fires (2.0 μg m−3) were more than twice that in the background cloud water (0.9 μg m−3). During periods when biomass burning plumes resided above cloud top, 16 of 29 cloud water samples were impacted due to instability in the entrainment interface layer with NO3 − levels reaching as high as 9.0 μg m−3. Nucleation scavenging of chloride depleted sea-salt is a source of cloud water NO3 −, with the lowest Cl−:Na+ ratio (1.5) observed in ship-influenced samples. Surface aerosol measurements show that NO3 − concentrations peak in the particle diameter range of 1.0–5.6 μm, similar to Na, Cl− and Si, suggesting that drop activation of crustal particles and sea salt could be an important source of NO3 − in cloud water. The contrasting behavior of NO3 − and SO4 2− is emphasized by the NO3 −:SO4 2− mass concentration ratio which is highest in cloud water (by more than a factor of two) followed by above cloud aerosol, droplet residual particles, and below cloud aerosol. Trends of a decreasing NO3 −:SO4 2− ratio with altitude in clouds are confirmed by parcel model studies due to the higher rate of in-cloud sulfate formation as compared to HNO3 uptake by droplets.Display Omitted
Keywords: Cloud water; Chloride depletion; Stratocumulus; Marine; Biomass burning; Sea-salt;
Atmospheric CO2, δ(O2/N2), APO and oxidative ratios from aircraft flask samples over Fyodorovskoye, Western Russia by S. van der Laan; I.T. van der Laan-Luijkx; C. Rödenbeck; A. Varlagin; I. Shironya; R.E.M. Neubert; M. Ramonet; H.A.J. Meijer (174-181).
We present atmospheric CO2 and δ(O2/N2) from flask samples taken on board aircraft over Fyodorovskoye (56°27′N, 32°55′E) at heights of 3000 m and 100 m between 1998 and 2008. The long-term trends for CO2 and δ(O2/N2) are similar for both sampling heights, and also similar to observations from marine background station Mace Head (Ireland) and coastal station Lutjewad (the Netherlands). The seasonal CO2 amplitude at 100 m was almost twice as large as at 3000 m and a phase shift in the seasonality of about two weeks between both sampling heights was observed. This indicates a dominant influence on CO2 in the boundary layer from the regional biosphere which is confirmed by analysis of the δ(O2/N2) to CO2 oxidative ratio (OR). Together with simulations with the TM3 model, our data suggest that the observed OR of −1.7 ± 0.2 in the free troposphere is mainly driven by exchange processes with the ocean. Within the boundary layer an OR of −0.89 ± 0.12 was observed which supports the results of other recent studies suggesting the commonly used value of −1.1 for biospheric OR is likely too low.
Keywords: Atmospheric CO2; Atmospheric δ(O2/N2); Oxidative ratio; Global carbon cycle; APO;
Source contributions to primary and secondary inorganic particulate matter during a severe wintertime PM2.5 pollution episode in Xi'an, China by Dexiang Wang; Jianlin Hu; Yong Xu; Di Lv; Xiaoyang Xie; Michael Kleeman; Jia Xing; Hongliang Zhang; Qi Ying (182-194).
Average PM2.5 concentrations of ∼250 μg m−3 and peak concentrations of ∼500 μg m−3 were observed in Xi'an, the largest city in Northwest China during an extreme event in January 2013. The source-oriented versions of the Community Multi-scale Air Quality (CMAQ) model with anthropogenic emissions from Emissions Database for Global Atmospheric Research (EDGAR) were used to study the source contributions of six different source categories including energy production, industries, transportation, residential activities, “other” (agriculture, biomass, waste burning, and biogenic sources), and windblown dust to primary and secondary inorganic PM2.5 (nitrate and sulfate) during this episode. The model generally captured the variation and magnitude of PM2.5 concentrations at monitoring sites. The monthly average concentration of the predicted PM2.5 in Xi'an was >200 μg m−3, comparing favorably with the measurement of ∼250 μg m−3. Predicted concentrations of elemental carbon (EC), organic aerosol (OA), sulfate, nitrate, and ammonium were 6, 35, 18, 22, and 12 μg m−3, respectively. Chemically unresolved PM2.5 components (PM2.5 Other) were ∼80 μg m−3. Industries and residential activities dominated EC, organic carbon (OC) and PM2.5 Other, contributing 85%, 95%, and 83%, respectively. Energy production (mainly coal combustion) was the dominating source for secondary nitrate, contributing 46%. Other local and upwind sources were also important, contributing 43% and 11% of total nitrate, respectively. Primary sulfate was ∼10 μg m−3 in vicinity surrounding point sources. Secondary sulfate from upwind sources was also important with concentrations of ∼4–5 μg m−3. Secondary sulfate formed by SO2 emitted from local sources was dominated by energy production. Based on the contributions of different sources to primary components and secondary nitrate and sulfate, the contributions of different sources to PM2.5 total mass in Xi'an during the extremely polluted months are: energy 5%, industries 58%, transportation 2%, residential activities 16%, dust 4%, and other (including other components, inexplicit sources, and upwind sources) 15%.
Keywords: Xi'an; Source apportionment; Particulate matter; WRF/CMAQ; EDGAR;
On-road and laboratory investigations on non-exhaust ultrafine particles from the interaction between the tire and road pavement under braking conditions by Jihyun Kwak; Sunyoup Lee; Seokhwan Lee (195-205).
We investigated the physical and chemical characteristics of non-exhaust ultrafine particles from on-road driving and laboratory measurements using a mobile sampling vehicle. The on-road driving and laboratory measurements during constant speed conditions revealed no enhancement of ultrafine particles. Under braking events, the total number concentrations of tire particles (TPs) sampled 90 mm above the road surface was 6 times higher with broader mode diameters when compared to 40 mm above the road surface. In contrast to braking events, under cornering conditions, the total number concentrations of TPs sampled 40 mm above the road surface were 50 times higher relative to 90 mm above the road surface. From the morphological and elemental analyses, it is likely that the ultrafine particles generated from the interaction between the tire and the road surface under braking conditions might originated from sulfur-containing materials or anti-oxidants which are contained in TPs, and/or graphite and solid lubricants which are mainly present in brake particles (BPs). However, Zn which was a distinguishing elemental marker of tire wear particles didn't show in EDS spectra. Further research would be required as to the exact emission source of ultrafine particles.Display Omitted
Keywords: Tire particles (TPs); Brake particles (BPs); On-road driving; Laboratory measurement; Morphological and elemental analyses;
Characteristics and source apportionment of VOCs measured in an industrial area of Nanjing, Yangtze River Delta, China by Junlin An; Bin Zhu; Honglei Wang; Yongyu Li; Xu Lin; Hui Yang (206-214).
Based on the data of volatile organic compounds (VOCs) collected continuously in the Nanjing industrial area, the VOCs temporal variability, photochemical reactivity, differences in tracer ratios, and source apportionment by principal component analysis/absolute principal component scores (PCA/APCS) were analyzed. The results showed that the total VOC concentration was 43.5 ppbv, which was 45.1% alkanes, 25.3% alkenes, 7.3% alkynes and 22.3% aromatics. There was an obvious seasonal variation in the of VOCs, with a maximum in summer and minimum in winter, as well as in the VOC components, with alkanes and alkynes highest in winter, alkenes highest in summer, and aromatics highest in spring. The VOCs exhibited significant diurnal variations, i.e. high at night and low during the day. The concentrations of nighttime VOCs were highest to lowest as follows: summer > autumn > spring > winter. By contrast, the concentrations of daytime VOCs were highest to lowest as follows: winter > summer > spring > autumn. The diurnal variation of the VOCs was the largest in autumn and the smallest in winter. The largest diurnal variation of alkanes and alkenes occurred in autumn, whereas the largest diurnal variation of aromatics and alkynes occurred in spring. Using the propylene-equivalent method, alkenes had the highest concentration, followed by aromatics and alkanes. The ratios of T/B, E/B and X/B were 1.2, 1.0 and 0.8, respectively, possibly due to the aging air mass. Based on the specific pollutant ratio method, the observation site was greatly affected by the surrounding industrial areas. The source analysis of the VOCs in the PCA/APCS mode showed that the sources consisted of industrial production sources, automobile emission sources, combustion sources, industrial production volatilization sources, solvent use sources and biogenic emission sources; in addition, there were seasonal variations. Overall, the sources related to industrial production activities accounted for 45–63% of the VOCs, followed by automobile emission sources, which accounted for 34–50%.
Keywords: Volatile organic compounds; Photochemical reactivity; Ozone formation potential; Source apportionment; PCA/APCS;
Polar organic marker compounds in atmospheric aerosol in the Po Valley during the Supersito campaigns — Part 2: Seasonal variations of sugars by Maria Chiara Pietrogrande; Dimitri Bacco; Marco Visentin; Silvia Ferrari; Patrizia Casali (215-225).
Four intensive experimental campaigns were conducted in the Po Valley (Northern Italy) in different seasons through the years 2012 and 2013, in the framework of the “Supersito” project. As a part of a study on polar tracers in atmospheric PM2.5, the present paper describes the abundances and temporal variations of sugars, as primary biogenic biomarkers, being the major form of photosynthetically assimilated carbon in the biosphere. The study includes primary saccharides (glucose, sucrose, arabinose, galactose and mycose), sugar alcohols (arabitol and mannitol) and anhydrosugars (levoglucosan, galactosan and mannosan).Strong seasonality was observed with total sugars concentration nearly 10 times higher in the cold seasons (mean 377 ng m−3) than in summer/spring (mean 36 ng m−3). Also sugar composition profiles varied seasonally, being dominated by anhydrosugars in fall and winter, i.e., levoglucosan (mean 271 ng m−3), followed by mannosan (mean 53 ng m−3) and galactosan (mean 29 ng m−3). These data indicate that in the cold seasons the biomass combustion for domestic heating is the main sugar source representing nearly 94% of the total saccharides mass measured in PM2.5. Accordingly, glucose, arabinose and galactose show the highest concentrations, since these saccharides are also emitted during the burning process as uncombusted biomass materials. In spring/summer the primary saccharides are dominant in PM2.5, with mannitol as the most abundant, followed by mycose, glucose and ribitol that are emitted by the terrestrial biomass, reflecting the higher sugar production and utilization by the ecosystem in the warm seasons.These results were confirmed by investigating other molecular markers, such as low-molecular-weight carboxylic acids and n-alkane homologs. Principal Component Analysis was applied to the data to extract three PCs that may be attributed to different saccharide sources, such as biomass burning and primary bio aerosol.
Keywords: Sugars; Atmospheric aerosol; Biomass burning; Biogenic emissions; Seasonal trend; Po Valley;
Sources and sinks of carbon dioxide in a neighborhood of Mexico City by E. Velasco; R. Perrusquia; E. Jiménez; F. Hernández; P. Camacho; S. Rodríguez; A. Retama; L.T. Molina (226-238).
Cities are the main contributors to the CO2 rise in the atmosphere. The CO2 released from the various emission sources is typically quantified by a bottom-up aggregation process that accounts for emission factors and fossil fuel consumption data. This approach does not consider the heterogeneity and variability of the urban emission sources, and error propagation can result in large uncertainties. These uncertainties might lead to unsound mitigation policies. Monitoring systems of greenhouse gases (GHG) based on independent methods are needed to validate the accuracy of the estimated emissions. In this context, direct measurements of CO2 fluxes that include all major and minor anthropogenic and natural sources and sinks from a specific district can be used to evaluate emission inventories. This study reports and compares CO2 fluxes measured directly using the eddy covariance (EC) method with emissions taken from the gridded local emissions inventory for the footprint covered by the EC flux system for a residential/commercial neighborhood of Mexico City. The flux measurements were conducted over 15-month period. No seasonal variability was found, but a clear diurnal pattern with morning and evening peaks in phase with the rush-hour traffic was observed. After adding contributions from human and soil respiration obtained by bottom-up approaches, and subtracting the CO2 sequestrated by vegetation calculated by applying biomass allometric equations and a growth predictive model to trees inventoried within the studied domain, results show that the current emissions inventory over-predicts 2.8 times the average daily flux measured on weekdays. Using traffic emissions data from a 2-year older inventory the difference decreased to 30%, suggesting that the traffic load for this part of the city is probably highly overestimated in the current emissions inventory. This study is expected to contribute to the verification capabilities of the GHG mitigation management of Mexico City, and to serve as a reference for other subtropical cities with similar urbanization patterns.
Keywords: Carbon dioxide; Eddy covariance; Urban emissions of greenhouse gases; Emissions inventory; Carbon sequestration;
Quantifying wildfires exposure for investigating health-related effects by H. Youssouf; C. Liousse; L. Roblou; E.M. Assamoi; R.O. Salonen; C. Maesano; S. Banerjee; I. Annesi-Maesano (239-251).
A wildfire is an uncontrolled fire in an area of combustible vegetation that occurs in the countryside or a wilderness area. The United Nation International Strategy for Disaster Reduction estimates that between 3 and 4 million km2 are affected by wildfire annually, with 18 000 km2 occurring in Europe. The Mediterranean region is one of the most affected regions by wildfires in Europe. Nearly 500 000 ha, on average, are burned annually by 50 000 wildfires in the countries of southern Europe bordering the Mediterranean Sea. Wildfires or biomass burning seriously damage ecosystems and affect public health. A major difficulty related to the assessment of health impact of wildfire emissions derives from the complexity of wildfire exposure assessments. Based on the literature, several methods, including satellite data, chemical transport models and, less often, personal exposure monitoring are available. However, few investigations have used methods allowing separating wildfires emissions from air pollutants emissions from urban sources having the same components. An inventory of wildfires occurred in Europe between 2006 and 2010 was obtained in terms of burnt areas, duration and related emissions of major air pollutants (black carbon, particulate matter), as obtained using a hybrid model that allows excluding anthropic sources of air pollution.
Keywords: Wildfires; Exposure; Assessment; Inventory; Wildfire emissions; Health effects;
Influence of local and regional sources on the observed spatial and temporal variability of size resolved atmospheric aerosol mass concentrations and water-soluble species in the Athens metropolitan area by Konstantinos Eleftheriadis; Klaus M. Ochsenkuhn; Theopisti Lymperopoulou; Angeliki Karanasiou; Panayiotis Razos; Maria Ochsenkuhn-Petropoulou (252-261).
The variability of common aerosol species in large Metropolitan urban areas is a major air quality issue with strong health impacts of large populations. PM10 and PM2.5 particulate matter samples were obtained at three sites characteristic of industrial, urban traffic and sub-urban residential areas in the Athens basin. Samples were analysed for anions (Cl−, NO3 −, SO4 2−) and cations (K+, Na+, Ca2+, Mg2+, NH4 +) using ion chromatography. The spatial and temporal variability for the particulate matter (PM) concentration mass and water-soluble ionic species concentrations for the investigated sites were studied. Mean PM fine concentration levels were 20% higher at the industrial and the central urban areas compared to those in the suburban area (24.2 μg/m3). The mean values for the coarse fraction at those two sites were two to three times higher compared to those at the suburban site (12.4 μg/m3). Comparable concentration levels of most species were observed in all areas, while SO4 2− and NO3 − differ at a significant level. Furthermore, the average size distributions of the mass and individual ions at the suburban site (NCSR Demokritos) showed a bimodal size distribution. SO4 2− and NH4 + have their main peak in the fine fraction while NO3 − showed equal distribution on the fine and coarse mode.. Good correlation was found for SO4 2− and NO3 − with Ca2+ and Na+ with Cl− for the coarse fraction in the industrial area. NH4 + was closely correlated with SO4 2− in the fine particles and in all areas. For the urban site the best correlations in coarse particulates were reported between Na+/Mg2+–Cl−, Ca2+/Mg2+–SO4 2−, explained by neutralization of acidic aerosol by soil dust and sea salt in the coarse fraction. Moreover, time weighted concentrations roses at the industrial and urban sites, showed no significant directional dependence, indicating either uniform generation of mainly the coarse species within the metropolitan area or major influence of the regional background for the fine aerosol species.
Keywords: PM10; PM2.5; Spatial variability; Urban aerosol size distribution; Ammonium sulphate; Calcium carbonate;
Exhaust particles of modern gasoline vehicles: A laboratory and an on-road study by Panu Karjalainen; Liisa Pirjola; Juha Heikkilä; Tero Lähde; Theodoros Tzamkiozis; Leonidas Ntziachristos; Jorma Keskinen; Topi Rönkkö (262-270).
Vehicle technology development and upcoming particle emission limits have increased the need for detailed analyses of particle emissions of vehicles using gasoline direct injection (GDI) techniques. In this paper the particle emission characteristics of modern GDI passenger cars were studied in a laboratory and on the road, with the focus on exhaust particle number emissions, size distributions, volatility and morphology. Both during acceleration and steady conditions the number size distribution of nonvolatile exhaust particles consisted of two modes, one with mean particle size below 30 nm and the other with mean particle size approximately 70 nm. Results indicate that both of these particles modes consisted of soot but with different morphologies. Both in laboratory and on the road, significant emissions of exhaust particles were observed also during decelerations conducted by engine braking. These particles are most likely originating from lubricant oil ash components. The semivolatile nucleation particles were observed in the laboratory experiments at high engine load conditions. Thus, in general, the study indicates that a modern gasoline vehicle can emit four distinctive types of exhaust particles. The differences in particle characteristics and formation should be taken into account in the development of emission control strategies and technologies and, on the other hand, in the assessment of the impact of particle emissions on environment and human health.Display Omitted
Keywords: Exhaust particles; Gasoline direct injection; Nucleation; Soot; Particle emissions;
Source apportionment of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in ambient air of an industrial region in Turkey by Yagmur Meltem Aydin; Melik Kara; Yetkin Dumanoglu; Mustafa Odabasi; Tolga Elbir (271-285).
Source apportionment is generally applied to a time series of data collected at a single site. However, in a complex airshed containing several different sources, it may be helpful to collect samples from multiple sites to ensure that some of them have low contributions from specific sources, thus the boundaries can be properly defined. Ambient air polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyls (PCB) samples (n = 160) were collected at 40 sites during four seasons (summer, fall, winter, and spring) between July 2009 and April 2010 in the heavily industrialized Aliaga region in Turkey to investigate their spatial, seasonal variations and to identify possible PAH and PCB sources. The newest version of EPA PMF (V5.0) having the capability of handling multiple site data was used for source apportionment. Five PAH sources were identified as biomass and coal combustion, iron–steel production, unburned crude oil and petroleum products, and diesel and gasoline exhaust emissions with contributions of 40, 27, 27, 3, and 3%, respectively. The sources of PCBs were identified as iron–steel production (consisting of steel-making and ship breaking activities), coal and wood combustion, and evaporative emissions from technical PCB mixtures with contributions of 57, 31, and 12%, respectively.
Keywords: Polycyclic aromatic hydrocarbons; Polychlorinated biphenyls; Positive matrix factorization; Source apportionment; Aliaga;
Effects of solid barriers on dispersion of roadway emissions by Nico Schulte; Michelle Snyder; Vlad Isakov; David Heist; Akula Venkatram (286-295).
Several studies have found that exposure to traffic-generated air pollution is associated with several adverse health effects. Field studies, laboratory experiments, and numerical simulations indicate that roadside barriers represent a practical method of mitigating the impact of vehicle emissions because near road concentrations are significantly reduced downwind of a barrier relative to concentrations in the absence of a barrier. These studies also show that the major effects of barriers on concentrations are: 1) the concentration is well mixed over a height roughly proportional to the barrier height, and this effect persists over several barrier heights downwind, 2) the turbulence that spreads the plume vertically is increased downwind of the barrier, 3) the pollutant is lofted above the top of the barrier. This paper ties these effects together using two semi-empirical dispersion models. These models provide good descriptions of concentrations measured in a wind tunnel study and a tracer field study. Their performance is best during neutral and stable conditions. The models overestimate concentrations near the barrier during unstable conditions. We illustrate an application of these models by estimating the effect of barrier height on concentrations during neutral, stable, and unstable conditions.
Keywords: Barrier; Air quality; Dispersion modeling; Roadway; Line source;
Determination of atmospheric nitrogen deposition to a semi-natural peat bog site in an intensively managed agricultural landscape by Miriam Hurkuck; Christian Brümmer; Karsten Mohr; Ludger Grünhage; Heinz Flessa; Werner L. Kutsch (296-309).
Rising levels of atmospheric nitrogen (N) deposition have been found to affect the primary productivity and species composition of most terrestrial ecosystems. Highly vulnerable ecosystems such as nutrient-poor bogs are expected to respond to increasing N input rates with a decrease in plant species diversity. Our study site – a moderately drained raised bog and one of only very few remaining protected peatland areas in Northwestern Germany – is surrounded by highly fertilised agricultural land and intensive livestock production. We quantified the annual deposition of atmospheric N over a period of two years. Dry deposition rates of different N species and their reactants were calculated from day and night-time concentrations measured by a KAPS denuder filter system. Dry N deposition amounted to 10.9 ± 1.0 kg N ha−1 yr−1 (year 1) and 10.5 ± 1.0 kg N ha−1 yr−1 (year 2). More than 80% of total deposited N was attributed to ammonia (NH3). A strong seasonality in NH3 concentrations and depositions could be observed. Day and night-time concentrations and depositions, however, did not differ significantly. Total N deposition including bulk N deposition resulted in about 25 kg N ha−1 yr−1. Our results suggest that the intensive agricultural land management of surrounding areas and strongly emitting animal husbandry lead to N inputs into the protected peatland area that exceed the ecosystem's specific critical load up to fivefold. This gives rise to the assumption that a further shift in plant species composition with a subsequent alteration of the local hydrological regime can be expected.
Keywords: Nitrogen deposition; Ammonia; Ombrotrophic bog; Denuder filter samplers; Critical load; Intensive agriculture;
Influence of meteorological factors on the atmospheric mercury measurement by a novel passive sampler by Haoli Guo; Huiming Lin; Wei Zhang; Chunyan Deng; Huanhuan Wang; Qianggong Zhang; Yating Shen; Xuejun Wang (310-315).
In recent years, an incentive for developing simple and cost-effective samplers that are capable of monitoring over an extended period and require nonattendance at remote locations was obvious. Compared to traditional active sampling approaches, passive samplers require no electric power and are more flexible in field deployment, thus they are more appropriate for screening applications and long-term sampling. However, the performance of passive samplers may be influenced by meteorological factors, therefore inducing bias for the result of passive sampling. In this study, the effects of temperature, relative humidity, and wind speed on the performance of a novel passive sampler for gaseous mercury were investigated. The meteorological factors were well controlled in an exposure chamber. The passive samplers were tested in different conditions: temperature ranging from −10 to 35 °C, relative humidity ranging from 25 to 90%, wind speed ranging from 0.5 to 5.0 m s−1. The results showed that temperature and relative humidity had no significant influence on the performance of the passive sampler. However, wind speed was found to have significant impact on the sampling rate of the passive sampler. Wind correction should be considered when making comparisons among samplings with different average wind speeds. In the field application in Beijing and Tibet site, the passively measured data were well correlated with the active measurements.
Keywords: Passive sampler; Atmospheric mercury; Sampling rate; Meteorological factors; Exposure chamber;
A review of fundamental drivers governing the emissions, dispersion and exposure to vehicle-emitted nanoparticles at signalised traffic intersections by Anju Goel; Prashant Kumar (316-331).
Signalised traffic intersections (TIs) are considered as pollution hot-spots in urban areas, but the knowledge of fundamental drivers governing emission, dispersion and exposure to vehicle-emitted nanoparticles (represented by particle number concentration, PNC) at TIs is yet to be established. A number of following key factors, which are important for developing an emission and exposure framework for nanoparticles at TIs, are critically evaluated as a part of this review article. In particular, (i) how do traffic- and wind-flow features affect emission and dispersion of nanoparticles? (ii) What levels of PNCs can be typically expected under diverse signal- and traffic-conditions? (iii) How does the traffic driving condition affect the particle number (PN) emissions and the particle number emission factors (PNEF)? (iv) What is the relative importance of particle transformation processes in affecting the PNCs? (v) What are important considerations for the dispersion modelling of nanoparticles? (vi) What is extent of exposure at TIs with respect to other locations in urban settings? (vii) What are the gaps in current knowledge on this topic where the future research should focus? We found that the accurate consideration of dynamic traffic flow features at TIs is essential for reliable estimates of PN emissions. Wind flow features at TIs are generally complex to generalise. Only a few field studies have monitored PNCs at TIs until now, reporting over an order of magnitude larger peak PNCs (0.7–5.4 × 105 cm−3) compared with average PNCs at typical roadsides (∼0.3 × 105 cm−3). The PN emission and thus the PNEFs can be up to an order of magnitude higher during acceleration compared with steady speed conditions. The time scale analysis suggests nucleation as the fastest transformation process, followed by dilution, deposition, coagulation and condensation. Consideration of appropriate flow features, PNEFs and transformation processes emerged as important parameters for reliable modelling of PNCs at TIs. Computation of respiratory deposition doses (RDD) based on the available PNC data suggest that the peak RDD at TIs can be up to 12-times higher compared with average RDD at urban roadsides. Systematic field and modelling studies are needed to develop a sound understanding of the emissions, dispersion and exposure of nanoparticles at the TIs.Display Omitted
Keywords: Airborne nanoparticles; Number size distribution; Traffic intersections; Particle dynamic; Exposure assessment;
Preliminary measurement-based estimates of PAH emissions from oil sands tailings ponds by Elisabeth Galarneau; Bruce P. Hollebone; Zeyu Yang; Jasmin Schuster (332-335).
Tailings ponds in the oil sands region (OSR) of western Canada are suspected sources of polycyclic aromatic hydrocarbons (PAHs) to the atmosphere. In the absence of detailed characterization or direct flux measurements, we present preliminary measurement-based estimates of the emissions of thirteen priority PAHs from the ponds. Using air concentrations measured under the Joint Canada-Alberta Oil Sands Monitoring Plan and water concentrations from a small sampling campaign in 2013, the total flux of 13 US EPA priority PAHs (fluorene to benzo[ghi]perylene) was estimated to be upward from water to air and to total 1069 kg y−1 for the region as a whole. By comparison, the most recent air emissions reported to Canada's National Pollutant Release Inventory (NPRI) from oil sands facilities totalled 231 kg y−1. Exchange fluxes for the three remaining priority PAHs (naphthalene, acenaphthylene and acenaphthene) could not be quantified but evidence suggests that they are also upward from water to air. These results indicate that tailings ponds may be an important PAH source to the atmosphere that is missing from current inventories in the OSR. Uncertainty and sensitivity analyses lend confidence to the estimated direction of air–water exchange being upward from water to air. However, more detailed characterization of ponds at other facilities and direct flux measurements are needed to confirm the quantitative results presented herein.Display Omitted
Keywords: Oil sands; Tailings ponds; Polycyclic aromatic hydrocarbons; PAHs; Air–water exchange; Volatilization;
Ambient air pollution and hypertensive disorders of pregnancy: A systematic review and meta-analysis by Hui Hu; Sandie Ha; Jeffrey Roth; Greg Kearney; Evelyn O. Talbott; Xiaohui Xu (336-345).
Hypertensive disorders of pregnancy (HDP, including gestational hypertension, preeclampsia, and eclampsia) have a substantial public health impact. Maternal exposure to high levels of air pollution may trigger HDP, but this association remains unclear. The objective of our report is to assess and quantify the association between maternal exposures to criteria air pollutants (ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter ≤10, 2.5 μm) on HDP risk. PubMed, EMBASE, MEDLINE, Current Contents, Global Health, and Cochrane were searched (last search: September, 2013). After a detailed screening of 270 studies, 10 studies were extracted. We conducted meta-analyses if a pollutant in a specific exposure window was reported by at least four studies. Using fixed- and random-effects models, odds ratios (ORs) and 95% CIs were calculated for each pollutant with specific increment of concentration.Increases in risks of HDP (OR per 10 ppb = 1.16; 95% CI, 1.03–1.30) and preeclampsia (OR per 10 ppb = 1.10; 95% CI, 1.03–1.17) were observed to be associated with exposure to NO2 during the entire pregnancy, and significant associations between HDP and exposure to CO (OR per 1 ppm = 1.79; 95% CI, 1.31–2.45) and O3 (OR per 10 ppb = 1.09; 95% CI, 1.05–1.13) during the first trimester were also observed. Our review suggests an association between ambient air pollution and HDP risk. Although the ORs were relatively low, the population-attributable fractions were not negligible given the ubiquitous nature of air pollution.
Keywords: Air pollution; Pregnancy-induced hypertension; Hypertensive disorders of pregnancy; Gestational hypertension; Preeclampsia; Meta-analysis;
Estimation of CO2 effluxes from suburban forest floor and grass using a process-based model by J.A. Chun; K. Szlavecz; M. Bernard; D. Ferrer; J. Hom; N. Saliendra (346-352).
Carbon dioxide is an important greenhouse gas, and its atmospheric concentration has been predicted to increase in the future. The objective of this study was to quantify the soil CO2 efflux in a suburban area including mixed deciduous forest and grass by numerically modeling the CO2 transport through the soil profile. Three stations per land-cover (forest and grass) were selected at the Cub Hill site (MD, USA), where the US Forest Service operates an urban flux tower. Six VAISALA CO2 sensors (Vaisala Inc., Finland) per monitoring station were horizontally installed at 6 different depths (soil surface, 0.02, 0.05, 0.10, 0.20, and 0.30 m from the soil surface) in the mid of May, 2011. Temperature and volumetric soil moisture measurements were taken using thermistors and EC-5 sensors (Decagon devices, Pullman, WA, USA) that were installed at the same depths as the CO2 sensors except for the soil surface. These data were recorded every 10 min. To evaluate the numerical model (SOILCO2), CO2 efflux using the standard chamber method was measured once a week. The CO2 effluxes from the standard chamber method ranged from 3.32 × 10−9 to 7.28 × 10−8 m3 m−2 s−1 and 6.79 × 10−9 to 1.45 × 10−7 m3 m−2 s−1 for forest and grass, respectively. The CO2 effluxes from “bare” soil at the grass site varied with the range of 3.63 × 10−8 to 9.37 × 10−8 m3 m−2 s−1. The “pulse effect” (a rapid increase of CO2 concentrations right after rainfall events) in grass, where changes in soil moisture were larger than in the forest, was more apparent than in the forest. Diurnal patterns similar to those of temperature were observed from CO2 profiles in soils. The SOILCO2 model estimated the soil CO2 effluxes with coefficients of correlation of 0.64 and 0.76 at forest and grass, respectively, and root mean square error (RMSE) of 1.58 × 10−8 and 2.06 × 10−8 m3 m−2 s−1 for forest and grass, respectively. This study suggests that the SOILCO2 model can provide a better understanding of the contribution of the soil ecosystem to the carbon cycle in suburban environments including mixed deciduous forest and grass.
Keywords: CO2 efflux; CO2 profiles; CO2 transport; SOILCO2; Pulse effect;
Developing Singapore Driving Cycle for passenger cars to estimate fuel consumption and vehicular emissions by Sze-Hwee Ho; Yiik-Diew Wong; Victor Wei-Chung Chang (353-362).
Singapore has pledged to attain 7–11% Business-As-Usual carbon emissions reduction by 2020. Road transport sector is a significant source of carbon emissions, estimated to be the third largest sector in Singapore. A current gap in environmental evaluation for road transport activities in Singapore is the lack of a representative driving cycle for passenger cars (64% of the total population of 974,170 vehicles). This Singapore Driving Cycle (SDC) is hence developed for Singapore roads and traffic conditions. A chase-car (instrumented vehicle) was used to collect on-road data along 12 designed routes, and circulation driving on highly utilized arterial roads (including those in Central Business District (CBD) and both inner and outer ring roads fringing the CBD area). The SDC was thus hence constructed, with consideration of road type proportions, time periods and desired distance, duration and peak-lull proportion. In essence, the SDC is a 2400-s speed–time profile to represent the driving pattern for passenger car in Singapore. Microscopic estimation model (CMEM) shows that, as compared to SDC, the New European Driving Cycle (NEDC) underestimates most of the vehicular emissions (fuel, CO2, HC and NO x by 5%, 5%, 22% and 47%, respectively) and overestimates CO by 8%. The SDC is thus more suitable than the NEDC that is currently in use in Singapore; the SDC can be used to generate more accurate fuel consumption and emissions ratings for various uses (for example, inventory of vehicular emissions and fuel economy labelling).
Keywords: Driving cycle; Chase-car; Microtrip; Expressway; Arterial road;
A WRF–CMAQ study on spring time vertical ozone structure in Southeast Texas by Xiangshang Li; Bernhard Rappenglück (363-385).
A WRF–SMOKE–CMAQ modeling system was used to simulate vertical profiles of ozone, temperature and wind as well as surface ozone and meteorology during the Study of Houston Atmospheric Radical Precursors (SHARP) in May 2009. WRF and CMAQ sensitivity studies were conducted to define a proper combination of model configurations.With objective analysis WRF showed considerable skills in simulating temperature and wind profiles. CMAQ did well in replicating daily regional average ozone, with only minor overprediction for most of the days. According to the surface ozone statistics and the ozone biases along the vertical profiles, the model displayed little sensitivity to the two CMAQ model options: (i) fixed night time PBL height vs. WRF calculated night time PBL heights, and (ii) the combination of the Euler-backward iterative chemistry schemes and Yamartino advection (EBI/YAMO) vs. the Sparse-Matrix Vectorized Gear chemistry and Parabolic Method advection (SMV-GEAR/PPM) schemes. CMAQ shows substantial underprediction of ozone in the upper troposphere, but demonstrated fair skills in reproducing the ozone profile in the lower to middle troposphere, with typically a few ppb negative biases which tend to increase with height. However, the model usually cannot reproduce high variability in the ozone profiles due to the fixed default profiles and lack of data assimilation capability. While the default CMAQ static profile setup for boundary condition (BC) does not properly reflect the actual dynamic atmosphere, it remains a reasonable choice, since using downscaled real-time global chemistry model BCs demands considerable efforts and would still depend on the performance of the global model.
Keywords: WRF; CMAQ; Radiosondes; Ozonesondes; Houston;
An overview of the physico-chemical characteristics of dust at Kanpur in the central Indo-Gangetic basin by Amit Misra; Abhishek Gaur; Deepika Bhattu; Subhasish Ghosh; Anubhav Kumar Dwivedi; Rosalin Dalai; Debajyoti Paul; Tarun Gupta; Vinod Tare; Sumit Kumar Mishra; Sukhvir Singh; Sachchida Nand Tripathi (386-396).
The optical, chemical, and physical properties of dust over the Indo-Gangetic basin are presented based on a campaign mode experiment conducted at Kanpur (26.52ºN, 80.23ºE), India, during April to July, 2011. During the study period, heavy dust storms and onset of south-west Indian Monsoon occurred. Based on physico-chemical characteristics, four aerosol types were identified in the region: background aerosol, dust dominated aerosol, pollution dominated aerosol, and mixed aerosol. The classification of aerosol types was found to be consistent with various aerosol properties examined and backtrajectory analysis. In addition to the locally generated aerosols, there were both short and long range transported aerosols. Aerosols of oceanic origin were encountered during late June, and July.
Keywords: Dust; Indo-Gangetic basin; Aerosol classification;
Analysis of secondary organic aerosols from ozonolysis of isoprene by proton transfer reaction mass spectrometry by Satoshi Inomata; Kei Sato; Jun Hirokawa; Yosuke Sakamoto; Hiroshi Tanimoto; Motonori Okumura; Susumu Tohno; Takashi Imamura (397-405).
To understand the mechanism of formation of the secondary organic aerosols (SOAs) produced by the ozonolysis of isoprene, proton transfer reaction mass spectrometry (PTR-MS) was used to identify the semi-volatile organic compounds (SVOCs) produced in both the gaseous and the aerosol phases and to estimate the gas–aerosol partitioning of each SVOC in chamber experiments. To aid in the identification of the SVOCs, the products were also studied with negative ion-chemical ionization mass spectrometry (NI-CIMS), which can selectively detect carboxylic acids and hydroperoxides. The gaseous products were observed by on-line PTR-MS and NI-CIMS, whereas the SVOCs in SOAs collected on a filter were vaporized by heating the filter and were then analysed by off-line PTR-MS and NI-CIMS. The formation of oligomeric hydroperoxides involving a Criegee intermediate as a chain unit was observed in both the gaseous and the aerosol phases by NI-CIMS. PTR-MS also detected oligomeric hydroperoxides as protonated molecules from which a H2O molecule was eliminated, [M−OH]+. In the aerosol phase, oligomers involving formaldehyde and methacrolein as chain units were observed by PTR-MS in addition to oligomeric hydroperoxides. The gas–aerosol partitioning of each component was calculated from the ion signals in the gaseous and aerosol phases measured by PTR-MS. From the gas–aerosol partitioning, the saturated vapour pressures of the oligomeric hydroperoxides were estimated. Measurements by a fast-mobility-particle-sizer spectrometer revealed that the increase of the number density of the particles was complete within a few hundred seconds from the start of the reaction.
Keywords: Criegee intermediate; Isoprene ozonolysis; Partitioning; Proton transfer reaction mass spectrometry; Secondary organic aerosol;
Production-based emissions, consumption-based emissions and consumption-based health impacts of PM2.5 carbonaceous aerosols in Asia by Kei Takahashi; Keisuke Nansai; Susumu Tohno; Masato Nishizawa; Jun-ichi Kurokawa; Toshimasa Ohara (406-415).
This study determined the production-based emissions, the consumption-based emissions, and the consumption-based health impact of primary carbonaceous aerosols (black carbon: BC, organic carbon: OC) in nine countries and regions in Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand, China, Taiwan, South Korea, and Japan) in 2008. For the production-based emissions, sectoral emissions inventory of BC and OC for the year of 2008 based on the Asian international input–output tables (AIIOT) was compiled including direct emissions from households. Then, a multiregional environmental input–output analysis with the 2008 AIIOT which was originally developed by updating the table of 2000 was applied for calculating the consumption-based emissions for each country and region. For the production-based emissions, China had the highest BC and OC emissions of 4520 Gg-C in total, which accounted for 75% of the total emissions in the nine countries and regions. For consumption-based emissions, China was estimated to have had a total of 4849 Gg-C of BC and OC emissions, which accounted for 77% of the total emissions in the Asia studied. We also quantified how much countries and regions induced emissions in other countries and regions. Furthermore, taking account of the source–receptor relationships of BC and OC among the countries and regions, we converted their consumption-based emissions into the consumption-based health impact of each country and region. China showed the highest consumption-based health impact of BC and OC totaling 111 × 103 premature deaths, followed by Indonesia, Japan, Thailand and South Korea. China accounted for 87% of the sum total of the consumption-based health impacts of the countries/regions, indicating that China's contribution to consumption-based health impact in Asia was greater than its consumption-based emissions. By elucidating the health impacts that each country and region had on other countries and from which country the impacts were received, we demonstrated that the characteristics of the consumption-based health impact varied significantly by country and region. We also determined the difference in the health impacts to other countries and regions due to the domestic final demand of each country and region, and the health impact due to the domestic final demand of that country or region.
Keywords: Premature deaths; Organic carbon; Black carbon; Consumption-based accounting; Multiregional input–output analysis; Source–receptor relationship;
Impact of long-range transport of aerosols on the PM2.5 composition at a major metropolitan area in the northern Kyushu area of Japan by Naoki Kaneyasu; Shigekazu Yamamoto; Kei Sato; Akinori Takami; Masahiko Hayashi; Keiichiro Hara; Kazuaki Kawamoto; Tomoaki Okuda; Shiro Hatakeyama (416-425).
In view of the recent rapid economic growth and accompanying energy consumption in the East Asian region, particularly in China, there is much concern about the effects of emitted particulate pollutants on human health. We have thus investigated the impact of long-range transport of aerosols on urban air quality in the upwind areas of Japan by comparing the PM2.5 composition collected for multiple years in Fukuoka, a representative metropolis in the Kyushu area, and in Fukue Island, located 190 km southwest of Fukuoka. Daily averaged PM2.5 concentrations in Fukuoka and Fukue were almost identical. PM2.5 concentrations at these sites were dominated by sulfate and particulate organics, and their fluctuation patterns were similar except for organics in the warm season. In contrast, those of nitrate and elemental carbon differed substantially between the sites. In addition, the ratios of Pb/Zn and Cd/Pb in Fukuoka were close to the reported values in Beijing. Non-sea-salt sulfate concentration in Fukuoka measured in this study and reported in the past measurements apparently coincided with the decadal SO2 emission change in China reported in a recent emission inventory. Therefore, we conclude that even in a city as large as Fukuoka, the PM2.5 concentration in the northern part of the Kyushu area is primarily dominated by the inflow of long-range transported aerosols throughout the year, except in the summer, rather than local air pollution emitted at each site.
Keywords: PM2.5; Long-range transport; East Asia; Sulfate; Metallic element; NAAQS;
Reprint of: Number concentrations and elemental compositions of aerosol particles observed at Mt. Kiso-Komagatake in central Japan, 2010–2013 by Yuji Zaizen; Hiroaki Naoe; Hiroshi Takahashi; Yasuhito Igarashi (426-434).
Aerosols in the lower troposphere over Japan are considered being influenced by those transported from Asian continent by westerly winds. In this study, we investigated the seasonal variation of aerosol number concentrations measured by means of optical particle counters at Mt. Kiso-Komagatake (2610 m altitude) in central Japan during the period from January 2010 to May 2013. We also collected aerosol samples in different seasons during part of the observation period and investigated their elemental compositions using transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDX). The seasonal variation of the number concentrations suggested that accumulation-mode particles (particle diameter > 0.3 μm) increased during late spring perhaps owing to gas-to-particle conversion by means of photochemical reactions. The number concentrations of supermicron particles (>1 μm) were highest in spring, during which Asian dust events were frequent. Short-duration spikes in aerosol number concentrations, which were attributed to long-range transport from the Asian continent, were frequently observed in all seasons except summer. TEM analysis indicated that sulfate was the predominant component of accumulation-mode particles throughout the year. The number fraction of carbonaceous particles was also considerable, especially in samples in fall. The predominant components of supermicron particles collected during winter, spring and fall, and summer were sulfate, minerals, and sea salt, respectively. Our results suggest that the lower tropospheric air over central Japan is strongly influenced by long-range transport of aerosols in all seasons except summer.
Keywords: Particle number concentration; Elemental composition; The free troposphere;
Modification of Asian-dust particles transported by different routes – A case study by Yuji Zaizen; Hiroaki Naoe; Hiroshi Takahashi; Kikuo Okada (435-446).
Two separate Asian dust events occurred before and after the passage of a cold front over Japan on 21 March 2010. According to back trajectories and a model simulation, the two dusty air-masses originated from the same region in Mongoria or northern China and were transported over different routes to Japan. Samples of aerosol particles from both airmasses were collected at Tsukuba and Mt. Haruna and examined by single-particle analysis using a transmission electron microscope and an energy dispersive X-ray analyzer. The mixing properties of mineral aerosol were quite different in the two airmasses and size ranges. In the prefrontal airmass, which were associated with pollution, most of fine (<1 μm) mineral aerosol was internally mixed with sulfate. On the contrary, mineral aerosols in the postfront airmass, which were relatively natural, were mostly externally mixed. In the latter case, the internal mixing was associated with Ca, however in the former case, mixing processes not concerning mineralogy was suggested.
Keywords: Asian dust; Electron microscopy; Size distribution; Mineral aerosol; Mixing state;
Characteristics of atmospheric aerosols containing heavy metals measured on Fukue Island, Japan by Takehiro Hidemori; Tomoki Nakayama; Yutaka Matsumi; Takashi Kinugawa; Akihiro Yabushita; Masafumi Ohashi; Takao Miyoshi; Satoshi Irei; Akinori Takami; Naoki Kaneyasu; Ayako Yoshino; Ryota Suzuki; Yayoi Yumoto; Shiro Hatakeyama (447-455).
To investigate transport and chemical compositions of fine aerosols in the East Asian region, aerosol chemical components and their mixing states were measured at Fukue Island in the spring of 2010. Off-line chemical analyses using an ion chromatographic analyzer and an inductively coupled plasma–mass spectrometer for the aerosols sampled by a high volume sampler have also been conducted. The mixing state and temporal variation of number concentrations of the particles containing lead (Pb) and vanadium (V) were studied by using a laser ionization single–particle aerosol mass spectrometer (LISPA-MS). The temporal variation of number concentrations of particles containing Pb measured by the LISPA-MS is well consistent with those obtained by the chemical analysis of the aerosols sampled by the high volume sampler. The Pb-containing particles were classified into four types from the statistical analysis on the basis of the single-particle mass spectra with assists of laboratory experiments. It is estimated that 52% of observed particles containing Pb were originated from coal combustion. The concentration-weighted trajectory (CWT) analysis suggests that these particles are mainly transported from China continent. The V-containing particles were classified into three types. The 41% of V-containing particles were internally mixed with sea salt and the result of CWT analysis suggests that the potentially anthropogenic V-containing particles possibility emitted from ships are mixing with sea salt in the region that is highly loaded with sea salt in the Pacific Ocean.
Keywords: Particulate matter; Single-particle mass spectrometer; Lead; Vanadium; Concentration-weighted trajectory analysis;
Aerial observations of air masses transported from East Asia to the Western Pacific: Vertical structure of polluted air masses by Shiro Hatakeyama; Keisuke Ikeda; Sayuri Hanaoka; Izumi Watanabe; Takemitsu Arakaki; Hiroshi Bandow; Yasuhiro Sadanaga; Shungo Kato; Yoshizumi Kajii; Daizhou Zhang; Kikuo Okuyama; Takashi Ogi; Toshiyuki Fujimoto; Takafumi Seto; Atsushi Shimizu; Nobuo Sugimoto; Akinori Takami (456-461).
There has been only limited information about the vertical chemical structure of the atmosphere, so far. We conducted aerial observations on 11, 12, and 14 December 2010 over the northern part of the East China Sea to analyze the spatial distribution of atmospheric pollutants from East Asia and to elucidate transformation processes of air pollutants during the long-range transport. On 11 December, a day on which Asian dust created hazy conditions, the average PM10 concentration was 40.69 μg m−3, and we observed high concentrations of chemical components such as Ca2+, NO3 –, SO4 2−, Al, Ca, Fe, and Zn. The height of the boundary layer was about 1200 m, and most species of pollutants (except for dust particles and SO2) had accumulated within the boundary layer. In contrast, concentrations of pollutants were low in the boundary layer (up to 1000 m) on 12 December because clean Pacific air from the southeast had diluted the haze. However, we observed natural chemical components (Na+, Cl–, Al, Ca, and Fe) at 3000 m, the indication being that dust particles, including halite, were present in the lower free troposphere. On 14 December, peak concentrations of SO2 and black carbon were measured within the boundary layer (up to 700 m) and at 2300 m. The concentrations of anthropogenic chemical components such as NO3 –, NH4 +, and Zn were highest at 500 m, and concentrations of both anthropogenic and natural chemical components (SO4 2−, Pb, Ca2+, Ca, Al, and Fe) were highest at 2000 m. Thus, it was clearly indicated that the air above the East China Sea had a well-defined, layered structure below 3000 m.
Keywords: Aerial observation; Asian dust; East China Sea; Ionic aerosol component; Metallic element;
Aerial observation of nitrogen compounds over the East China Sea in 2009 and 2010 by Hiroshi Fujiwara; Yasuhiro Sadanaga; Junki Urata; Yoshihiko Masui; Hiroshi Bandow; Keisuke Ikeda; Sayuri Hanaoka; Izumi Watanabe; Takemitsu Arakaki; Shungo Kato; Yoshizumi Kajii; Daizhou Zhang; Kazutaka Hara; Toshiyuki Fujimoto; Takafumi Seto; Kikuo Okuyama; Takashi Ogi; Akinori Takami; Atsushi Shimizu; Shiro Hatakeyama (462-470).
Aerial observations of atmospheric pollutants were made over the East China Sea to analyze the transport of air pollutants, especially nitrogen oxides, from East Asia. Three flights each were conducted in October 2009 (autumn) and December 2010 (winter). Onboard measurements of gaseous total odd nitrogen species, gaseous nitric acid (HNO3(g)), O3, SO2, CO and black carbon were made and particles were collected on filters for ionic and metal component analyses. The NO3 −(p)/T.NO3 (T.NO3 = HNO3(g) + NO3 −(p); NO3 −(p) indicates particulate nitrate) ratios were less than 0.5 in most cases. Exceptions were 17 October and 11 December, when high concentrations of dust particles (Kosa) were transported. The average T.NO3/NO y (NO y indicates total odd nitrogen species) ratio in winter was 0.59, and that in autumn was 0.71. In addition, positive and negative correlations between NO y − T.NO3 and ozone were observed in autumn and winter, respectively. These results indicate that the main components of NO y − T.NO3 are NO x and its descendant photochemical products, such as peroxyacyl nitrates and alkyl nitrates, in winter and autumn, respectively. Ratios of Na+ to Cl− + NO3 − in particles were close to the seawater ratio for observations in both autumn and winter, save for the Kosa events. The main NO3 −(p) formation process was the reaction of HNO3(g) with sea salt aerosols during autumn and winter. On the other hand, NO3 −(p) was generated by the reaction of HNO3(g) with dust particles and sea salt during the Kosa events. The fraction of NH4NO3 in NO3 −(p) was very small.
Keywords: Aerial observation; Nitrate; Total odd nitrogen species; East Asia;
Concentration variations of total reactive nitrogen and total nitrate during transport to Fukue Island and to Cape Hedo, Japan in the marine boundary layer by Akie Yuba; Yasuhiro Sadanaga; Akinori Takami; Shiro Hatakeyama; Yoshihiko Masui; Toshimasa Ohara; Seiichiro Yonemura; Shungo Kato; Yoshizumi Kajii; Hiroshi Bandow (471-478).
We conducted continuous measurements of NO y and total nitrate (T.NO3 = HNO3 + NO 3 − ( p ) ) at Fukue Island, Nagasaki, and Cape Hedo, Okinawa, Japan. We compared variations of NO y or T.NO3 concentrations measured at two remote sites when the air masses were originated from the same regions of the Asian Continent. Long-range transport events from the Asian Continent were extracted by CO concentration peaks at Fukue and Hedo and backward trajectory analyses. We compared the transport time difference at two sites from the Asian continent with the ratios of NO y at Hedo to that at Fukue (=R(NO y )) to find the predominant factor in NO y removal. R(NO y ) were less than unity and decreased with the transport time difference. The ratios of NO y /CO at Hedo to those at Fukue (R(NO y /CO)) was assumed to be affected by the deposition process. R(NO y /CO) showed negative correlation with transport time difference as the same the case of R(NO y ). This indicates that NO y was mainly removed by deposition rather than dilution. Air mass ages were classified by the ratio of T.NO3 to NO y at Fukue: T.NO3/NO y < 0.2 was fresh air, 0.2–0.4 was middle-aged, and greater than 0.4 was aged. The ratios of T.NO3/NO y at Hedo to those at Fukue (R(T.NO3/NO y )) in the fresh air mass were greater than unity. In contrast, R(T.NO3/NO y ) values in the aged air mass were unity and were less correlated with transport time difference. This indicates that T.NO3 generation proceeded in fresh air mass. On the other hand, T.NO3 generation rate was comparable to removal rate in the aged air mass. According to the relationship between R(NO y /CO) and transport time difference, the removal rate constant and NO y lifetime were (1.24 ± 0.33) × 10−5 s−1 and 18–31 h, respectively.
Keywords: Total reactive nitrogen; Long-range transport; Removal rate; Lifetime; East Asia;
Spatial and temporal variations of chemicals in the TSP aerosols simultaneously collected at three islands in Okinawa, Japan by Takemitsu Arakaki; Sotaro Azechi; Yuka Somada; Moriaki Ijyu; Fumiya Nakaema; Yuya Hitomi; Daishi Handa; Yoshito Oshiro; Youichi Miyagi; Ai Tsuhako; Hitomi Murayama; Yumi Higaonna; Akira Tanahara; Akihide Itoh; Soko Fukushima; Kazuaki Higashi; Yui Henza; Rin Nishikawa; Hibiki Shinjo; Hongyan Wang (479-485).
East Asia’s rapid economic growth has led to concerns about the emission of air pollutants. We collected total suspended particle (TSP) aerosol samples simultaneously at three islands in Okinawa, Japan, which are downwind of East Asia, during the Asian dust season, to examine the spatial and temporal variations and chemical transformations of major chemicals in the aerosols. Weekly samples were collected from July 2008 to June 2010, and the concentrations of water-soluble cations, anions, and organic carbon (WSOC) were determined (n = 303). Spatial distribution analysis showed that monthly mean concentrations of non-sea-salt (nss)- SO 4 2 − in the spring (Asian dust season) decreased with increasing distance from Asia, while the trend for NO 3 − was less evident, suggesting that chemical transformation affected the long-range transport of certain chemicals. Temporal variation analysis showed that concentrations of nss- SO 4 2 − , NO 3 − , and WSOC during the spring were about 2.0, 2.4, and 1.8 times those in the summer (cleaner air mass from the Pacific Ocean), respectively. This study demonstrated that air pollutants were transported from the Asian continent to the Okinawa islands and affected the air quality in the region. There may also be impacts on ecosystems, because increased concentrations of particulate NO 3 − could increase nutrient levels around the Okinawa islands.
Keywords: Water-soluble chemicals; Aerosol; East Asia; Okinawa;
Development of a polarization optical particle counter capable of aerosol type classification by Hiroshi Kobayashi; Masahiko Hayashi; Koichi Shiraishi; Yoshinobu Nakura; Takayuki Enomoto; Kazuhiko Miura; Hiroshi Takahashi; Yasuhito Igarashi; Hiroaki Naoe; Naoki Kaneyasu; Tomoaki Nishizawa; Nobuo Sugimoto (486-492).
We developed a polarization optical particle counter (POPC) for measuring the concentrations of aerosol types, which were classified using polarization information from particle-scattered light. Polarization sensors that detect P and S polarization components of scattered light were placed at a scattering angle of 120°. The polarization ratio is calculated as the ratio of the S component to the sum of the S and P components, and it is used to help distinguish proposed aerosol types. The POPC field observation was conducted in Fukuoka, located in the western part of Japan, in 2012. The classification rule for three aerosol types (mineral dust, air pollution, and sea-salt particles) was determined empirically on the basis of measurements during typical conditions dominated by each aerosol type. The mass concentration of each aerosol type was estimated from the POPC measurement with some assumptions. The results indicate independent seasonal variation in each aerosol mass concentration. Using black carbon as an indicator of anthropogenic aerosols, we show a correlation of 0.770 with our estimated pollution aerosol type.
Keywords: Polarization; Particle shape; Mineral dust; Aerosol type; Optical particle counter;
Effects of long-term exposure to ammonium sulfate particles on growth and gas exchange rates of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica seedlings by Masahiro Yamaguchi; Yoko Otani; Peiran Li; Hiroshi Nagao; I. Wuled Lenggoro; Atsushi Ishida; Kenichi Yazaki; Kyotaro Noguchi; Satoshi Nakaba; Kenichi Yamane; Katsushi Kuroda; Yuzou Sano; Ryo Funada; Takeshi Izuta (493-500).
To clarify the effects of long-term exposure to ammonium sulfate (AS) particles on growth and physiological functions of forest tree species, seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to submicron-size AS particles during two growing seasons from 3 June 2011 to 8 October 2012. The mean sulfate concentration in PM2.5 increased during the exposure inside the chamber in 2011 and 2012 by 2.73 and 4.32 μg SO4 2− m−3, respectively. No significant effects of exposure to AS particles were detected on the whole-plant dry mass of the seedlings. These results indicate that the exposure to submicrometer AS particles at the ambient level for two growing seasons did not significantly affect the growth of the seedlings. No significant effects of exposure to AS particles were found on the net photosynthetic rate in the leaves or needles of F. crenata, C. sieboldii and L. kaempferi seedlings. Also, in the previous-year needles of C. japonica seedlings, exposure to AS particles significantly reduced the net photosynthetic rate, which may be caused by the reduction in the concentration of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco). On the contrary, in current-year needles of C. japonica seedlings, net photosynthetic rate significantly increased with exposure to AS particles, which may be the result of increases in stomatal conductance and concentrations of Rubisco and chlorophyll. Furthermore, exposure to AS particles correlated with an increase in concentrations of NH4 +, free amino acid and total soluble protein, suggesting that AS particles may be deliquesced, absorbed into the leaves and metabolized into amino acid and protein. These results suggest that net photosynthesis in the needles of C. japonica is relatively sensitive to submicron-size AS particles as compared with the other three tree species.
Keywords: Ammonium sulfate particles; Forest tree species; Physiological function; Plant growth; PM2.5;
A numerical study of the effects of aerosol hygroscopic properties to dry deposition on a broad-leaved forest by Genki Katata; Mizuo Kajino; Kazuhide Matsuda; Akira Takahashi; Ko Nakaya (501-510).
To investigate the impact of hygroscopic growth on dry deposition onto forest canopies, numerical simulations of PM2.5 sulfate deposition using a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) ware performed. The scheme of particle dry deposition in SOLVEG was extended for application to a broad-leaved forest. An aerosol hygroscopic model based on the widely used κ-Köhler theory was incorporated into the model to calculate water uptake by the aerosols. The model accurately reproduced essential turbulent exchange fluxes (momentum, heat, and water vapor) over the canopies and the soil temperature and moisture for a deciduous broad-leaved forest in central Japan. Temporal variations in the measured PM2.5 sulfate deposition velocity were generally reproduced by the model. By considering an increase in particle diameter due to hygroscopic growth, the prediction accuracy of the modeled deposition velocity under humid conditions was improved. Numerical experiments for varying aerosol size distributions and hygroscopic properties showed that the geometric mean diameter and hygroscopicity of particles have a large influence on hygroscopic growth levels. The results also suggested that the deposition velocity of wet particles increased due to hygroscopic growth when the relative humidity (RH) was approximately 50%, and that the velocity reached five times greater than that under dry conditions when RH exceeded 95%.
Keywords: Sulfate aerosols; Dry deposition; Relative humidity; Hygroscopic growth; Multi-layer land surface model; SOLVEG;
Foliar rinse study of atmospheric black carbon deposition to leaves of konara oak (Quercus serrata) stands by Hiroshi Hara; Takumi Kashiwakura; Kyo Kitayama; Sonoko Deothea Bellingrath-Kimura; Tomohiro Yoshida; Masao Takayanagi; Sadamu Yamagata; Naoto Murao; Hiroshi Okouchi; Hiroko Ogata (511-518).
Dry deposition of Black Carbon (BC) to the actual leaves of konara oak (Quercus serrata) was evaluated in a foliar rinse method in an experimental forest in the suburbs of Tokyo, Japan in order to explore deposition levels and vertical profile within the forest. At three heights of the forest of 20 m height, 20 m, 15 m, and 6 m or 4 m, leaves were sampled on a weekly basis for a couple of months in 2011 and 2012 and subjected to rinsing with water and chloroform. The BC in the rinse solution was collected on a quartz fiber filter and determined by spectrophotometry. The BC mass deposited to leaves increased with height and this profile pattern was generally maintained in the study period. The specific BC mass deposited to leaves showed considerable fluctuations with time, but the deposited BC increased rapidly with time in the bud flushing stage, then attained to a plateau, and began to decrease as the defoliation advanced. The plateau is a result of a simple accumulation with time and occasional removal due to rainfall and strong winds. The maximum BC mass deposited to leaves per leaf surface unit area occurred in June where the level was 10–15 mg-BC m−2. The rate of BC mass deposited to leaves at the time of leaves growing was determined to be 0.237 and 0.277 mg-BC m−2 day−1 for measurements in 2011 and 2012, respectively. On the basis of the observed BC mass deposited to the leaves, BC mass deposited to leaves per forest floor unit area estimated with LAI showed a strong seasonality. The BC mass deposited to leaves per forest floor unit area was compared to the deposition flux from the atmosphere to the forest canopy, which would be interpreted as indicating that 30% of atmospheric BC deposition to the canopy was retained on the leaves in time of leaves growing.
Keywords: Aerosol; Black carbon; Dry deposition; Foliar rinsing; Forest; Japan;
Physicochemical properties and ability to generate free radicals of ambient coarse, fine, and ultrafine particles in the atmosphere of Xuanwei, China, an area of high lung cancer incidence by Senlin Lu; Fei Yi; Xiaojie Hao; Shang Yu; Jingjing Ren; Minghong Wu; Feng Jialiang; Shinich Yonemochi; Qingyue Wang (519-528).
The link between the high incidence of lung cancer and harmful pollutants emitted by local coal combustion in Xuanwei, Yunnan province, China, has been a focus of study since the 1980s. However, the mechanisms responsible for the high lung cancer rate remain unclear, necessitating further study. Since a close relationship between ambient air particle pollution and respiratory diseases exists, we sampled size-resolved ambient particles from the atmosphere of Xuanwei. In our indoor experiment, cutting-edge methods, including scanning electron microscopy coupled with energy dispersive X-ray detection (SEM/EDX), particle-induced X-ray emission (PIXE), electronic paramagnetic resonance (EPR) and the cell-free DCFH-DA assay, were employed to investigate the physicochemical properties, the potential to generate free radicals and the oxidative potential of ambient coarse (diameter, 1.8–10 μm), fine (diameter, 0.1–1.8 μm), and ultrafine (diameter, <0.1 μm) particles. We found the total mass concentrations of the size-resolved particles collected in spring were higher than that in early winter. Mass percentage of fine particles accounted for 68% and 61% of the total particulate mass in spring and in early winter samples, respectively, indicating that fine particles were the major component of the Xuanwei ambient particulate matters. On the other hand, the results of SEM/EDX analysis showed that the coarse particles were dominated by minerals, the fine particles by soot aggregates and fly ashes, and the ultrafine particles by soot particles and unidentified particles. Our PIXE results revealed that crustal elements (Ca, Ti Si, Fe) were mainly distributed in coarse particles, while trace metals (Cr, Mn, Ni, Cu, Zn, Pb) dominated in the fine particle fraction, and S, a typical element emitted by coal combustion, mainly resided in fine particles collected from the winter atmosphere. EPR results indicated that the magnitude of free radical intensity caused by size-resolved particles followed these patterns: fine particles > coarse particles > ultrafine particles for spring samples and ultrafine particles > fine particles > coarse particles for winter samples. Cell-free DCFH assay results conclusively showed that all of the measured particle suspensions displayed a higher oxidative potential than the negative control. The correlation coefficient (R 2) between free radical intensity and fluorescent intensity generated by the size-resolved particles was 0.535 and 0.507 for the spring and winter seasons, respectively, implying that ambient air particles in the Xuanwei atmosphere have the ability to generate free radicals, and fine and ultrafine particles could be hazardous to local residents.
Keywords: Size-resolved ambient particles; Chemical elements; Free radicals; Oxidative potential; Xuanwei; China;
Toxicological effects of polycyclic aromatic hydrocarbons and their derivatives on respiratory cells by Eiko Koike; Rie Yanagisawa; Hirohisa Takano (529-536).
Polycyclic aromatic hydrocarbons (PAHs) are found in ambient aerosols and particulate matter. Experimental studies have shown that PAHs and related chemicals can induce toxicological effects. The present study aimed to investigate the effects of PAHs and their derivatives on the respiratory and immune systems and the underlying mechanisms. The human bronchial epithelial cell line BEAS-2B was exposed to PAHs and their derivatives, and the cytotoxicity and proinflammatory protein expression were then investigated. A cytotoxic effect was observed in BEAS-2B exposed to PAH derivatives such as naphthoquinone (NQ), phenanthrenequinone (PQ), 1-nitropyrene (1-NP), and 1-aminopyrene (1-AP). In addition, 1,2-NQ and 9,10-PQ showed more effective cytotoxicity than 1,4-NQ and 1,4-PQ, respectively. Pyrene showed a weak cytotoxic effect. On the other hand, naphthalene and phenanthrene showed no significant effects. Pyrene, 1-NP, and 1-AP also increased intercellular adhesion molecule-1 expression and interleukin-6 production in BEAS-2B. The increase was partly suppressed by protein kinase inhibitors such as the epidermal growth factor receptor-selective tyrosine kinase inhibitor and nuclear receptor antagonists such as the thyroid hormone receptor antagonist. The present study suggests that the toxicological effects of chemicals may be related to the different activities resulting from their structures, such as numbers of benzene rings and functional groups. Furthermore, the chemical-induced increase in proinflammatory protein expression in bronchial epithelial cells was possibly a result of the activation of protein kinase pathways and nuclear receptors. The increase may partly contribute to the adverse health effects of atmospheric PAHs.
Keywords: Polycyclic aromatic hydrocarbons; Bronchial epithelial cells; Proinflammatory cytokines; Intracellular signaling pathway;
Exacerbation of daily cough and allergic symptoms in adult patients with chronic cough by Asian dust: A hospital-based study in Kanazawa by Tomomi Higashi; Yasuhiro Kambayashi; Noriyuki Ohkura; Masaki Fujimura; Sayaka Nakanishi; Tomokazu Yoshizaki; Kiyofumi Saijoh; Kazuichi Hayakawa; Fumihisa Kobayashi; Yoshimasa Michigami; Yoshiaki Hitomi; Hiroyuki Nakamura (537-543).
The health effects associated with Asian dust have attracted attention due to the rapid increase in the number of Asian dust events in East Asia in recent years. The aim of this study was to investigate the associations between Asian dust and daily cough, as well as allergic symptoms, in adult patients who suffer from chronic cough. We enrolled 86 adult patients from Kanazawa University Hospital, Japan, who were diagnosed with asthma, cough variant asthma, atopic cough or a combination of these conditions. From January to June 2011, subjects recorded their symptoms in a diary every day. Asian dust and non-Asian dust periods were defined according to the dust extinction coefficient, measured using the light detection and ranging (LIDAR). The daily levels of total suspended particulates, polycyclic aromatic hydrocarbons (PAHs) and coexisting factors related to allergies, such as the Japanese cedar pollen count, were measured. McNemar's test showed that there were significantly more cough-positive patients during Asian dust periods than during the non-Asian dust period (p = 0.022). In addition, during Asian dust periods when the daily levels of Japanese cedar pollen, Japanese cypress pollen and PAHs were elevated, there were significantly more patients who experienced itchy eyes than during the non-Asian dust period (p < 0.05). On the other hand, there were no significant differences in the allergic symptoms, including sneezing or a runny nose and nasal congestion. This is the first report to show that Asian dust triggers cough and allergic symptoms in adult patients with chronic cough.
Keywords: Allergic symptoms; Asian dust; Asthma; Chronic cough; Daily cough symptom;
Reprint of: Effects of Asian dust on daily cough occurrence in patients with chronic cough: A panel study by Tomomi Higashi; Yasuhiro Kambayashi; Noriyuki Ohkura; Masaki Fujimura; Satoshi Nakai; Yasushi Honda; Kiyofumi Saijoh; Kazuichi Hayakawa; Fumihisa Kobayashi; Yoshimasa Michigami; Anyenda Enoch Olando; Yoshiaki Hitomi; Hiroyuki Nakamura (544-551).
Asian dust, known as kosa in Japanese, is a major public health concern. In this panel study, we evaluated the effects of exposure to kosa on daily cough occurrence. The study subjects were 86 patients being treated for asthma, cough variant asthma, or atopic cough in Kanazawa University Hospital from January 2011 to June 2011. Daily mean concentrations of kosa and spherical particles were obtained from light detection and ranging (LIDAR) measurements, and were categorized from Grade 1 (0 μg/m3) to 5 (over 100 μg/m3). The association between kosa and cough was analyzed by logistic regression with a generalized estimating equation. Kosa effects on cough were seen for all Grades with potential time lag effect. Particularly at Lag 0 (the day of exposure), a dose-response relationship was observed: the odds ratios for Grades 2, 3, 4, and 5 above the referent (Grade 1) were 1.111 (95% confidence interval (CI): 0.995-1.239), 1.171 (95% CI: 1.006-1.363), 1.357 (95% CI: 1.029-1.788), and 1.414 (95% CI: 0.983-2.036), respectively. Among the patients without asthma, the association was higher: the odds ratios for Grades 2, 3, 4 and 5 were 1.223 (95% CI: 0.999-1.497), 1.309 (95% CI: 0.987-1.737), 1.738 (95% CI: 1.029-2.935) and 2.403 (95% CI: 1.158-4.985), respectively. These associations remained after adjusting for the concentration of spherical particles or particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5). Our findings demonstrate that kosa is an environmental factor which induces cough in a dose-response relationship.
Keywords: Asian dust; Kosa; Chronic cough; Daily cough symptom; PM2.5;
Improved methods for elemental analysis of atmospheric aerosols for evaluating human health impacts of aerosols in East Asia by Tomoaki Okuda; James J. Schauer; Martin M. Shafer (552-555).
This paper provides improved elemental analysis methods for the characterization of atmospheric particulate matter (PM) samples. With the aim of developing an approach for comprehensive trace element analysis of small mass of PM samples, we coupled an enhanced microwave-assisted acid digestion method with high-resolution magnetic sector inductively coupled plasma-mass spectrometry (SF-ICP-MS). We also propose a rapid and simple method using energy dispersive X-ray fluorescence spectrometry (EDXRF) that has secondary targets and three-dimensional polarization optics for screening elemental composition of PM. We obtained the concentrations of 44 elements ranged from 10−3 to 105 μg/g by SF-ICP-MS, and 16 elements ranged from 101 to 105 μg/g by EDXRF. The analytic results obtained by these two methods agreed well. Comprehensive analysis for a large set of elements was demonstrated by using the improved SF-ICP-MS method, while EDXRF coupled with fundamental parameter (FP) quantification method can analyze several selected elements as fast as 900 s (15 min) per sample with only minimal sample pretreatment. We provide two possible choices of analysis methods for elucidating elemental composition of PM according to the number of samples, target elements, sample amounts, time and cost for analysis required.
Keywords: EDXRF; Microvolume microwave-assisted acid digestion; Particulate matter; SF-ICP-MS; Trace elements;